The present invention pertains to a process for the preparation of aromatic polymers and more particularly pertains to a process for the preparation of aromatic polyamides via the palladium catalyzed carbonylation and condensation of aromatic primary amines and aromatic trifluoromethane sulfonates.
Aromatic polyamides are commonly prepared by the condensation of aryl diacid chlorides and aromatic diamines in a dipolar aprotic solvent. This method has the shortcomings of requiring low temperatures in order to achieve high molecular weight polymers and being subject to the limited variety of available aromatic diacid chlorides and the hydrolytically unstable nature of diacid chlorides.
Japanese Kokai 123823, published May 16, 1989, and Yoneyama et al, Macromolecules, Vol. 21, 1988, pp. 1908-1911 disclose the use of a Heck carbonylation reaction, to produce low molecular weight polyamides, by the reaction of aromatic dibromides and diamines, in the presence of carbon monoxide and a palladium catalyst. U.S. Pat. No. 5,104,971, issued Apr. 14, 1992, to Perry et al, discloses use of a Heck carbonylation reaction to produce high molecular weight polyamides, by the reaction, under pressure, of aromatic diiodides and diamines, in the presence of carbon monoxide and a palladium catalyst The use of Heck carbonylation reactions to produce polyamides avoids the problems presented by acid chlorides, but requires appropriately substituted halides and the removal or recycling of halide generated during the coupling reaction It is therefore highly desirable to provide an improved method for the preparation of aromatic polyamides.
Amide formation from aryl and vinyl trifluoromethane sulfonates is reported in Ortar, et al, Tetrahedron Letters, Vol. 26, (1985) pp. 1109-1112 and Ortar, et al, Tetrahedron Letters, Vol. 27, (1986) pp. 3931-3934.